Trunked communication systems are known. Such systems typically use a base site including a resource controller and a number of transceivers. The base site then services communication units located within a service coverage area. A number of transceivers are required for the base site to service multiple simultaneous conversations. Since only a limited frequency spectrum is available for mobile communication units the number of simultaneous conversations within a particular service coverage area is mainly limited by the size of the spectrum available. The size of a service coverage area is typically chosen to be as large as possible (to minimize infrastructure complexity and cost).
Communication units desiring service transmit a request for service over a control resource (such as a dedicated control channel comprised of a particular frequency or TDM time slot) reserved for that purpose. The communication unit upon requesting service is granted a communication resource (such as a frequency pair or TDM time slot) for transmitting and receiving communications. The base site then supports the communication transaction through local transceivers.
As the number of communication units has increased trunked systems have become congested. To reduce congestion service coverage areas have been reduced in size. A smaller coverage area provides for reduced numbers of mobile units within a given area and, therefore, less competition for available spectrum. A smaller coverage area also allows transmitting units to reduce transmitted power levels. Reducing the power levels of base sites and communication units allows for the same frequencies to be used by other communication units located in surrounding service coverage areas (geographic re-use) without interference.
While geographic re-use can result in significant increases in efficiency the need for communications between units within widely dispersed groups still exists. A need therefore exists for other means/methodologies for increasing the efficiency of the use of communication resources, while retaining large coverage area trunking system services.